A capacitance type sensor is generally used as a device for converting into an electric signal the intensity and direction of a force applied by an operator. For example, as an input device for a game machine used is a device incorporated as a capacitance type force sensor (so-called joy stick) for inputting operations in multidimensional directions.
Using the capacitance type sensor, an operation quantity with a predetermined dynamic range can be input as the intensity of a force applied by the operator. Such a sensor may be used in the form of a two-dimensional or three-dimensional force sensor capable of detecting each directional component divided from the applied force. In particular, a capacitance type sensor in which a capacitance element is made up of two electrodes and a force is detected on the basis of a change in capacitance value due to a change in interval of the electrodes has a merit that a cost reduction can be intended by simplifying the construction. Therefore, sensors of this type have been put in practical use in various fields.
For example, Japanese Patent Application Laid-open No. 7(1995)-200164 discloses a capacitance type sensor as illustrated in FIG. 30. The capacitance type sensor 510 is made up of a substrate 520, an elastic rubber sheet 530 provided on the substrate 520, an electrode 540 provided on the lower surface of the elastic rubber sheet 530, electrodes 500 to 504 (see FIG. 31) provided on the upper surface of the substrate 520, a holder plate 560 for supporting and fixing the elastic rubber sheet 530 to the substrate 520, and an electronic device 580 provided on the lower surface of the substrate 520. As illustrated in FIG. 31, the electrodes 500 to 504 are constituted by electrodes 501 and 502 disposed symmetrically in relation to Y axis, electrodes 503 and 504 disposed symmetrically in relation to X axis, and an annular electrode 500 disposed outside them. An outer peripheral portion of the electrode 540 is in contact with the electrode 500, which is grounded, so that the electrode 540 is also grounded through the electrode 500.
When an operator depresses the elastic rubber sheet 530, the electrode 540 is deformed downward in accordance with the depression force to change the respective distances between it and the four electrodes 501 to 504. The capacitance values of the respective capacitance elements formed between the four electrodes 501 to 504 and the electrode 540 change accordingly. Thus, by detecting the changes in capacitance values, the intensity and direction of the force applied by the operator can be known.
However, though the capacitance type sensor 510 illustrated in FIGS. 30 and 31 is suitable for use as a device (force sensor) for recognizing the intensity of the force when the operator depresses the elastic rubber sheet 530, it is unsuitable for use as a device having a switch function for switching between two different states (e.g., ON and OFF states). Therefore, in case of incorporating into an apparatus the capacitance type sensor 510 as a device having a switch function in each direction, it is hard to use the capacitance type sensor 510 in its original form and there is a necessity of provision of a separate switch function corresponding to each direction.
Accordingly, it is an object of the present invention to provide capacitance type sensors that can be used as either of devices for recognizing the intensity of a force in each direction and devices having switch functions.